Elucidating the molecular basis of the rumen and small intestine dysbiosis complex in cattle

• Applicant: Dr. Thomas Hartinger
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry
• Term: from 2020 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 447776988

Meeting energy and nutrient demands of high-performing ruminants along with avoiding intestinal dysbiosis and disease states is key for efficient milk and beef production and among the biggest challenges in modern ruminant livestock farming. High-grain feeding is the major trigger for gastrointestinal disorders, particularly in the rumen, i.e. leading to acute or sub-acute rumen acidosis (SARA) with damaged barrier function and a dysbiotic microbial community. Decreasing starch fermentability (e.g. by replacing corn for wheat) reduces the incidences of rumen acidosis, but also shifts starch fermentation to lower gut segments, where adverse effects on the large intestine’s microbiota and epithelial barrier function have already been shown. In consequence, such local impairments are likely to expand to systemic inflammation states, which substantially impair the ruminant’s health and productivity. When escaping the rumen, the large quantities of fermentable yet undegraded substrates will first reach the small intestine and induce microbial growth and fermentation in this gut segment. Consequently, this is expected to impair enzymatic digestion and absorptive processes, as well as stimulate dysbiotic shifts in the small intestine, hereby termed small intestinal dysbiosis. However, knowledge on the impact of high-grain feeding on the small intestinal microbiota and barrier function is lacking. As both the duodenum and the jejunum have a generally high permeability, the small intestine can indeed be a major, but so far overlooked, ‘leaky gut’ region during high-grain challenges. We therefore believe that SARA and small intestinal acidosis are interrelated, they build a complex, and only under consideration of both segments in a holistic approach, gut health and therefore system-wide health and productivity of high-performing ruminants can be achieved. We will apply state-of-the-art molecular methods to investigate microbial community compositions, the intestinal milieu and epithelial integrity, as well as local and systemic inflammation patterns in vivo. Further, ex vivo-based Ussing-chamber experiments on ruminal and small intestinal epithelia will generate detailed knowledge on the expression of genes relevant for the absorptive capacity of nutrients and the barrier function in response to acidotic insults. In this context, the proposed project will provide invaluable and novel information on microbiota dynamics and adaptive metabolic capacities of rumen and small intestinal epithelia of ruminants during acidotic challenges, which thus empowers the development of efficient strategies to promote and maintain gut health in high-performing ruminants.

• DFG Programme: WBP Fellowship
• International Connection: Austria
• Host: Professor Dr. Qendrim Zebeli